Genetic parameters for lean meat yield, meat quality, reproduction and feed efficiency traits for Australian pigs 2. Genetic relationships between production, carcase and meat quality traits

Data from 1799 Large White and 1522 Landrace boars were used to obtain genetic correlations between production, carcase and meat quality traits. Variance components were obtained by REML procedures applying an average information algorithm. Traits analysed included average daily gain from 3 to 18 weeks of age (ADG1) and average daily gain, feed intake and feed conversion ratio from 18 to 22 weeks of age (ADG2, FDINT, FCR). Carcase traits included two backfat measurements and one muscle depth measurement taken on the live animal using realtime ultrasound and on the carcase using Hennesy Chong equipment. Further carcase traits included weight of the whole back leg (BLW) and weight of the ham (LMW). Meat quality traits included pH recorded 45 min (pH45) and 24 h after slaughter (pH24), colour of the m. longissimus dorsi (CLD) and m. multifidus dorsi (CMD), drip loss percentage (DLP) and intramuscular fat content (IMF). ADG1 was genetically a different trait than ADG2 (genetic correlation (rg): 0.32+/-0.23). Genetic correlations between these two traits and backfat measurements were favourable for ADG1 (rg: -0.35 to -0.21, +/-0.13 to 0.22) and unfavourable for ADG2 (rg: 0.29 to 0.48, +/-0.18 to 0.22). A lighter CLD was genetically related to a higher DLP and a lower pH. Estimates were higher between pH24, CLD and DLP (absolute rg: 0.71 to 0.83, +/-0.11 to 0.14) than between pH45 and further meat quality traits (absolute rg: 0.12 to 0.44, +/-0.23 to 0.24). Increasing IMF will improve other meat quality traits (rg: 0.06 to 0.48, +/-0.19 to 0.24). Growth rate was genetically independent from meat quality traits (rg range: -0.31 to 0.35, +/-0.18 to 0.31) while selection for improved feed efficiency and increased leanness will increase the incidence of PSE meat (absolute rg range: 0.00 to 0.66, +/-0.14 to 0.31) and reduce IMF (rg: 0.16 to 0.34, +/-0.15 to 0.27). Meat quality traits should therefore be included in selection indices in order to avoid further deterioration as a result of selection for higher leanness and feed efficiency. (C) 2000 Elsevier Science B.V. All rights reserved.